This invention concerns adjustable wrenches and more particularly adjustable wrenches of the type having a fixed jaw and an aligned movable jaw with a corresponding V-shaped jaw face able to engage hex threaded fasteners over a range of sizes.
Adjustable wrenches having opposing flat faces such as the so-called "crescent" wrench can only engage a pair of opposite sides of a hex bolt head or nut so as to be of limited use by mechanics, as attempts to exert a substantial torque may round off the corners of the flats. This type of wrench is also bulky, limiting access to a nut or bolt head in tight quarters.
It has long been proposed to provide an adjustable wrench having opposing jaws each of which are formed with angled faces so that together both jaws engage four of the hex sides. This engagement greatly improves the ability to exert a torque on the bolt head or nut.
The necessity of maintaining alignment of the jaws with each other to properly engage the hex sides requires a more complex wrench configuration and imposes other requirements such that previously devised wrenches of this type have not been completely successful.
Typical is the wrench shown in U.S. Pat. No. 1,361,050 issued on Dec. 7, 1920 for a "Wrench." This design features a fixed vee-shaped jaw at one end of a slot and a movable vee-shaped jaw adjustably movable towards and away from the fixed jaw. The movable jaw is supported by machined gibs on the sides of the slot.
The machined gibs required by the construction of the wrench described in that patent involves costly manufacturing steps and may not perform satisfactorily in use due to weakness in the connections provided between some of the major components.
See also U.S. Pat. Nos. 1,697,764; 2,912,891; 1,284,731; and 258,673 for further examples of such adjustable wrenches.
The need for rugged precision support of the movable jaw has necessitated the use of jaw gibs and other costly measures.
A more recent version of this general approach is shown in U.S. Pat. No. 4,967,613 issued on Nov. 6, 1990 for a "Reversible Adjustable Wrench." That patent uses a captured thumbwheel as an adjustment nut engaged with a small diameter threaded shaft fixed to the movable jaw piece for carrying out the adjustment movement of the movable jaw.
This wrench has achieved some commercial success, but also has certain drawbacks. The movable jaw is primarily supported by the slot sides, necessitating relatively thick sidewalls on which side extension portions of the movable jaw ride to resist the large forces tending to tip the movable jaw piece when the handle exerts torque on the hex head fastener.
The wider side extension portions create an obstruction which requires greater clearance space around the nut or bolt head.
The thumbwheel and the thick slot sides together contribute to an overall bulkiness of the wrench.
All of the above wrenches are not particularly convenient to use for various reasons.
For example, the projecting jaw lips are typically sized at their outer end to fit the largest hex head for which the wrench is designed. Thus, the jaw often cannot fit into recessed openings for smaller nut sizes.
Often, the jaws incorporate side flanks which do not engage the hex shape and hence while adding bulk, do not contribute to the ability to exert torque on the fastener.
The object of the present invention is to provide an adjustable wrench which incorporates V-shaped jaws and body which is more compact, able to be used effectively in confined spaces, and enables precision guidance of the movable jaw, and is more conveniently adjustable in use, yet is simple, rugged, and capable of sustaining considerable torque without requiring costly manufacturing steps and special assembly tools in being constructed.